JPH11217455A - Rubber composition for sponge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for sponge having a good balance among flexibility, low compression set, and low-temperature properties and having good processability. SOLUTION: This composition mainly consists of (A) an ethylene copolymer rubber comprising ethylene, a 6-12C α-olefin, and a nonconjugated polyene and satisfying the requirements: (1) the molar ratio of the ethylene to the 6-12C α-olefin (ethylene/α-olefin ratio) is 40/60 to 80/20, (2) the iodine value is 15-45, (3) the Mooney viscosity (ML1+4 , 100 deg.C) is 40-150, and (4) the glass transition temperature (Tg) is -80- to -55 deg.C as measured with a differential scanning calorimeter(DSC), (B) a vulcanizer and/or a crosslinking agent, and (C) a blowing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition for a sponge, and more particularly, to flexibility, low compression set,
The present invention relates to a sponge rubber composition having a good balance of low-temperature properties and excellent processing properties.

[0002]

2. Description of the Related Art Ethylene / propylene / non-conjugated diene copolymer (EPDM) is excellent in weather resistance, heat resistance, cold resistance, ozone resistance, etc., and has hitherto been used for building materials, automobile parts, electric wire coating materials. Widely used in such as. However, with the recent high performance and long life of automobiles,
The performance requirements for these materials are becoming more stringent. Especially,
In the conventional EPDM sponge, improvement of the settability is a major problem. On the other hand, softness (sound when opening and closing the door) is also regarded as important, and it is necessary to respond to the demand for soft sponge products. However, the soft feeling and the low hetability are in a trade-off relationship, and it is extremely difficult to achieve both. In addition, although some low-hardness materials are required for some roll materials such as OA rolls and seal materials, conventional EPDM is hard. The compression set is inferior and not fully satisfactory.

On the other hand, a random copolymer comprising an α-olefin having 6 or more carbon atoms and a non-conjugated diene is disclosed in US Pat. Nos. 3,933,769 and 4,064,33.
No. 5,340,705 discloses a copolymer comprising an α-olefin having 6 or more carbon atoms, methyl-1,4-hexadiene and α, ω-diene; JP-A-5-202143 discloses that the number of carbon atoms is six.
Copolymers comprising the above α-olefin, α, ω-diene and other linear non-conjugated dienes are disclosed. However, in the case of these copolymers, when a large amount of α, ω-diene is used in order to secure sufficient mechanical properties,
There is a problem that a gel is easily generated in the copolymer, which easily adversely affects the mechanical properties, and it is not sufficient to use it as a sponge rubber or the like.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a good balance between flexibility and low compression set by using a specific ethylene copolymer rubber. Another object of the present invention is to provide a sponge rubber composition having excellent processing characteristics.

[0005]

The present invention provides (A) an ethylene copolymer rubber comprising ethylene, an α-olefin having 6 to 12 carbon atoms and a non-conjugated polyene and satisfying the following requirements: (B) An object of the present invention is to provide a rubber composition for a sponge containing a vulcanizing agent and / or a crosslinking agent, and (C) a foaming agent as main components (hereinafter, also referred to as “rubber composition”). The molar ratio of ethylene to an α-olefin having 6 to 12 carbon atoms (ethylene / α-olefin) is 40/60 to 80 /
20 Iodine value: 15 to 45 Mooney viscosity (ML _{1 + 4} , 100 ° C.): 40 to 150 Glass transition temperature (Tg) determined by a differential scanning calorimeter (DSC): −80 to −55 ° C.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene copolymer rubber (A) used in the rubber composition of the present invention is ethylene, having 6 carbon atoms.
To α-12 (hereinafter also referred to as “α-olefin”) and a non-conjugated polyene.
Examples of the α-olefin include 1-hexene,
4-methyl-1-pentene, 1-heptene, 5-methyl-1-hexene, 1-octene, 5-ethyl-1-hexene, 1-nonene, 1-decene, 1-dodecene, and the like, preferably, 1-hexene and 1-octene are used. These α-olefins can be used alone or in combination of two or more. The molar ratio of ethylene to the α-olefin in the ethylene copolymer rubber (ethylene / α-olefin is 40/60 to 80
/ 20, preferably in the range of 50/50 to 70/30 [requirement]. In this case, the above molar ratio is 40/6
If it is less than 0, the mechanical strength is inferior, while if it exceeds 80/20, the flexibility and the permanent compression set are not satisfied.

[0007] Non-conjugated polyenes include, for example,
5-ethylidene-2-norbornene, dicyclopentadiene, 5-propylidene-2-norbornene, 5-vinyl-2-norbornene, 2,5-norbornadiene,
Cyclic polyenes such as 1,4-cyclohexadiene, 1,4-cyclooctadiene and 1,5-cyclooctadiene; 1,4-hexadiene, 1,6-octadiene, 7
-Methyl-1,6-octadiene, 5,7-dimethyl-
Examples include chain polyenes having an internal unsaturated bond such as 1,6-octadiene and 1,7-nonadiene, and preferably 5-ethylidene-2-norbornene, dicyclopentadiene, 7-methyl-1,6- Octadiene,
5,7-dimethyl-1,6-octadiene. These non-conjugated polyenes can be used alone or in combination of two or more.

The iodine value of the (A) ethylene-based copolymer rubber is in the range of 15 to 45, preferably 20 to 35 [the above requirement]. In this case, if the iodine value is less than 15, the mechanical strength is poor, while if it exceeds 45, the rubber elasticity is impaired.

Further, (A) the Mooney viscosity (ML _{1 + 4} , 100 ° C.) (hereinafter also referred to as “Mooney viscosity”) of the ethylene copolymer rubber is 40 to 150, preferably 50
~ 120 [the above requirements].

Further, (A) the glass transition temperature Tg of the ethylene copolymer rubber determined by a differential scanning calorimeter (DSC) is -80 to -55 ° C, preferably -70 to -58.
It is in the range of ° C [the above requirements].

The (A) ethylene copolymer rubber used in the present invention can be produced by an appropriate method such as a gas phase polymerization method, a solution polymerization method, and a slurry polymerization method. These polymerization operations can be carried out in a batch system or a continuous system. In the above solution polymerization method or slurry polymerization method, an inert hydrocarbon is usually used as a reaction medium. Such inert hydrocarbon solvents include, for example, n-pentane, n-hexane, n-heptane, n-
Aliphatic hydrocarbons such as octane, n-decane and n-dodecane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and aromatic hydrocarbons such as benzene, toluene and xylene. These hydrocarbon solvents can be used alone or in combination of two or more. Further, the raw material monomer can be used as a hydrocarbon solvent.

Examples of the polymerization catalyst used for producing the above (A) ethylene copolymer rubber include, for example, V, T
An olefin polymerization catalyst comprising a compound of a transition metal selected from i, Zr and Hf and an organometallic compound can be exemplified. The transition metal compound and the organometallic compound can be used alone or in combination of two or more. As a particularly preferred example of such an olefin polymerization catalyst, a metallocene catalyst comprising a metallocene compound and an organoaluminum compound or an ionic compound which reacts with the metallocene compound to form an ionic complex can be mentioned. Hereinafter, the polymerization catalyst for producing the ethylene copolymer rubber (A) will be described more specifically, but a polymerization catalyst other than the following may be used in some cases.

As the metallocene catalyst, for example,
A catalyst comprising the following components (D) and (E) or a catalyst comprising the following components (F) and (G) is exemplified. Component (D) is a transition metal compound represented by the following general formula (I). In the formula, M is a metal of Group 4 of the periodic table, (C ₅ R _m ) is a cyclopentadienyl group or a substituted cyclopentadienyl group, and each R may be the same or different and includes a hydrogen atom, An alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, or two adjacent carbon atoms are bonded. E is an atom having a non-bonded electron pair, R 'is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, and a carbon atom having 7 to 8 carbon atoms. 40 alkaryl groups or 7 to 7 carbon atoms
40 is an aralkyl group, R ″ is an alkylene group having 1 to 20 carbon atoms, dialkyl silicon or dialkyl germanium, and is a group that binds two ligands;
Is 1 or 0; when s is 1, m is 4; n is a number smaller than the valence of E by 2; when s is 0, m is 5,
n is a number less than the valence of E; when n ≧ 2, each R ′ may be the same or different; each R ′ may be bonded to form a ring; and Q is a hydrogen atom A halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, and p and q are 0 to 4
And satisfies the relationship 0 <p + q ≦ 4.

Specific examples of component (D) include bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) ) Zirconium diphenyl, dimethylsilylbis (cyclopentadienyl) zirconium dichloride, dimethylsilylbis (cyclopentadienyl) zirconium dimethyl, methylenebis (cyclopentadienyl) zirconium dichloride, ethylenebis (cyclopentadienyl) zirconium dichloride, bis (Indenyl) zirconium dichloride, bis (indenyl) zirconium dimethyl, dimethylsilylbis (indenyl) zirconium dichloride, methylenebis (indenyl) zircon Umujikurorido, bis (4,
5,6,7-tetrahydroindenyl) zirconium dichloride, bis (4,5,6,7-tetrahydroindenyl) zirconium dimethyl, dimethylsilylbis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, dimethyl Silyl bis (4,5,6,7
-Tetrahydroindenyl) zirconium dimethyl, ethylenebis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dimethyl, dimethylsilyl Bis (3-methyl-1-cyclopentadienyl)
Zirconium dichloride, methylene bis (3-methyl-
1-cyclopentadienyl) zirconium dichloride,
Bis (t-butylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (3-t-butyl-1
-Cyclopentadienyl) zirconium dichloride, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2,4-dimethyl-1-cyclopentadienyl) zirconium dichloride, bis (1,2,2 4-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2,3,5-trimethyl-1-cyclopentadienyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, dimethylsilylbis (fluorenyl) zirconium dichloride, ( Fluorenyl) (cyclopentadienyl) zirconium dichloride, dimethylsilyl (fluorenyl) (cyclopentadienyl) zirconium dichloride, isopropylene (fluorenyl) (cyclopentadiene Le) zirconium dichloride, (t-butylamido) (1,2,3,4,5-pentamethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (t-butylamido) (2,3,
4,5-tetramethyl-1-cyclopentadienyl) zirconium dichloride, methylene (t-butylamide)
(2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dichloride, (phenoxy)
(1,2,3,4,5-pentamethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (o-phenoxy) (2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dichloride, methylene (O-phenoxy) (2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dichloride, ethylene (o-phenoxy) (2,3,4,5-tetramethyl-1-cyclopentadiene) (Enyl) zirconium dichloride, bis (dimethylamido) zirconium dichloride, bis (diethylamido) zirconium dichloride, bis (di-t-butylamido) zirconium dichloride, dimethylsilylbis (methylamido) zirconium dichloride, dimethylsilylbis (t-butylamide)
Examples include zirconium dichloride and the like, and compounds in which zirconium in these compounds is substituted with titanium or hafnium, but is not limited thereto. The transition metal compound may be used alone or
More than one species can be used in combination.

The component (E) is an aluminoxane compound having a unit represented by the following general formula (II), and although the chemical structure is not necessarily clear, a linear, cyclic or cluster compound, Alternatively, it is presumed to be a mixture of these compounds. — [Al (P) —O] — (II) wherein P is an alkyl group having 1 to 20 carbon atoms, and 6 to 4 carbon atoms.
An aryl group having 0, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, preferably a methyl group, an ethyl group, an isobutyl group, and particularly preferably a methyl group. The aluminoxane compound can be produced by a known method involving a reaction between water and the organoaluminum compound having at least one P group.
The proportion of the component (D) to the component (E) used is usually 1/1 to 1 / 100,000, preferably 1 in terms of the molar ratio of transition metal to aluminum atom (transition metal / aluminum atom). / 5 to 1 / 50,000.

Next, the component (F) is a transition metal alkyl compound represented by the following general formula (III). R ″ _s (C ₅ R _m ) _p (R ′ _n E) _q MR ″ ′ _4-pq (III) In the formula, M is a Group 4 metal of the periodic table, and (C ₅ R _m ) is a cyclopentadienyl group or a substituted cyclopentadienyl group, and each R may be the same or different and includes a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, Is an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, or two adjacent carbon atoms are bonded to form a 4- to 8-membered carbocyclic ring; R ′ is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms, or
40 is an aralkyl group, R ″ is an alkylene group having 1 to 20 carbon atoms, dialkyl silicon or dialkyl germanium, and is a group that binds two ligands;
Is 1 or 0; when s is 1, m is 4; n is a number smaller than the valence of E by 2; when s is 0, m is 5,
n is a number less than the valence of E, and when n ≧ 2, each R ′ may be the same or different, and each R ′ may be bonded to form a ring; C1-C20 alkyl group, C6-C40 aryl group, C7-C
An alkaryl group of 40 or an aralkyl group of 7 to 40 carbon atoms, p and q are integers of 0 to 3,
<P + q ≦ 4.

Specific examples of component (F) include bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diethyl, bis (cyclopentadienyl) zirconium diisobutyl, and bis (cyclopentadienyl) Zirconium diphenyl, bis (cyclopentadienyl) zirconium di {bis (trimethylsilyl) methyl}, dimethylsilylbis (cyclopentadienyl) zirconium dimethyl, dimethylsilylbis (cyclopentadienyl) zirconium diisobutyl, methylenebis (cyclopentadienyl) ) Zirconium dimethyl, ethylene bis (cyclopentadienyl) zirconium dimethyl, bis (indenyl) zirconium dimethyl, bis (indenyl) zirconium diisobutyl, dimethyl Rubis (indenyl) zirconium dimethyl, methylenebis (indenyl) zirconium dimethyl, ethylenebis (indenyl) zirconium dimethyl, bis (4,5,6,7-tetrahydroindenyl) zirconium dimethyl, dimethylsilylbis (4,5,6,7 -Tetrahydro-1-indenyl) zirconium dimethyl, ethylenebis (4,5,6,7-
Tetrahydro-1-indenyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (3-methyl-1-cyclopentadienyl) zirconium dimethyl, bis (t-
Butylcyclopentadienyl) zirconium dimethyl,
Dimethylsilylbis (3-t-butyl-1-cyclopentadienyl) zirconium dimethyl, bis (1,3-dimethylcyclopentadienyl) zirconium dimethyl,
Bis (1,3-dimethylcyclopentadienyl) zirconium diisobutyl, dimethylsilylbis (2,4-dimethyl-1-cyclopentadienyl) zirconium dimethyl, methylenebis (2,4-dimethyl-1-cyclopentadienyl) Zirconium dimethyl, ethylene bis (2,4-dimethyl-1-cyclopentadienyl) zirconium dimethyl, bis (1,2,4-trimethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (2,3,5-trimethyl) -1-cyclopentadienyl) zirconium dimethyl, bis (fluorenyl) zirconium dimethyl, dimethylsilylbis (fluorenyl) zirconium dimethyl, (fluorenyl)
(Cyclopentadienyl) zirconium dimethyl, dimethylsilyl (fluorenyl) (cyclopentadienyl)
Zirconium dimethyl, isopropylene (fluorenyl) (cyclopentadienyl) zirconium dimethyl,
(T-butylamide) (1,2,3,4,5-pentamethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (t-butylamide) (2,3,4,5-
Tetramethyl-1-cyclopentadienyl) zirconium dimethyl, methylene (t-butylamide) (2,3
4,5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, (phenoxy) (1,2,3
4,5-pentamethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (o-phenoxy)
(2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, methylene (o-phenoxy) (2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, Bis (dimethylamido) zirconium dimethyl, bis (diethylamido) zirconium dimethyl, bis (di-t-butylamido) zirconium dimethyl, dimethylsilylbis (methylamido) zirconium dimethyl, dimethylsilylbis (t-butylamido) zirconium dimethyl and the like, and compounds thereof Compounds obtained by substituting zirconium therein with titanium or hafnium include, but are not limited to. The above transition metal alkyl compounds can be used alone or in combination of two or more.

The transition metal alkyl compound may be synthesized and used in advance, or may be a transition metal halide in which R ″ in the general formula (III) is substituted with a halogen atom, and trimethylaluminum, triethylaluminum, diethylaluminum. It may be formed by bringing an organic metal compound such as monochloride, triisobutylaluminum, methyllithium, and butyllithium into contact in a reaction system.

The component (G) is an ionic compound represented by the following general formula (IV). In the formula, [L] ^{k +} is a Bronsted acid or a Lewis acid, M ′ is an element belonging to Groups 13 to 15 of the periodic table, and A ₁ to
_An is a hydrogen atom, a halogen atom, and a carbon number of 1 to 2, respectively.
0 alkyl group, C1-C30 dialkylamino group, C1-C20 alkoxyl group, C6-C40
An aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, a halogen-substituted hydrocarbon group having 1 to 40 carbon atoms,
An acyloxy group or an organic metalloid group having 1 to 20 carbon atoms, k is an ionic value of L, an integer of 1 to 3,
Is an integer of 1 or more, and q = (k × p).

Specific examples of component (G) include trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, methyl (di-n-butyl) ammonium tetraphenylborate, and tetraphenylborate. Dimethylanilinium borate, methylpyridinium tetraphenylborate, methyl tetraphenylborate (2-
Cyanopyridinium), methyl tetraphenylborate (4-cyanopyridinium), trimethylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluorophenyl) borate, tetrakis Methyl (penta-fluorophenyl) borate (di-n-butyl) ammonium, dimethylanilinium tetrakis (pentafluorophenyl) borate, methylpyridinium tetrakis (pentafluorophenyl) borate, methyl (2-cyanopyridinium) tetrakis (pentafluorophenyl) borate ), Methyl tetrakis (pentafluorophenylphenyl) borate (4-cyanopyridinium),
Dimethylanilinium tetrakis [3,5-di- (trifluoromethyl) phenyl] borate, ferrocenium tetraphenylborate, silver tetraphenylborate, ferrocenium tetrakis (pentafluorophenyl) borate, and the like, but are not limited thereto. is not. The above ionic compounds can be used alone or in combination of two or more.

The ratio of the component (F) to the component (G) used is usually 1 / 0.5 to molar ratio [(F) / (G)].
1/20, preferably in the range of 1 / 0.8 to 1/10. (A) The metallocene catalyst used for producing the ethylene copolymer rubber may be used by supporting at least a part of those components on a suitable carrier.
The type of carrier is not particularly limited, and any of inorganic oxide carriers, other inorganic carriers, and organic carriers can be used. In addition, there is no particular limitation on the loading method, and a known method may be appropriately used.

Next, among the vulcanizing agents and / or crosslinking agents (B) used in the present invention, examples of the vulcanizing agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur and insoluble sulfur; , Selenium, tellurium and other inorganic vulcanizing agents;
Examples include sulfur-containing organic compounds such as morpholine disulfide, alkylphenol disulfides, thiuram disulfides, and dithiocarbamates. These vulcanizing agents can be used alone or in combination of two or more. The amount of the vulcanizing agent is usually 0.1 to 10 parts by weight based on 100 parts by weight of the ethylene copolymer rubber (A).
Parts by weight, preferably 0.5 to 5 parts by weight.

It is to be noted that a vulcanization accelerator can be used in combination with the above vulcanizing agent. Examples of such a vulcanization accelerator include aldehyde ammonias such as hexamethylenetetramine; guanidines such as diphenylguanidine, di (o-tolyl) guanidine and o-tolyl-piguanide; thiocarbanilide and di (o-tolyl) Thioureas such as thiourea, N, N'-diethylthiourea, tetramethylthiourea, trimethylthiourea, dilaurylthiourea; mercaptobenzothiazole, dibenzothiazole disulfide, 2- (4-morpholinothio) benzothiazole, 2- (2,4-dinitrophenyl) -mercaptobenzothiazole, (N, N'-
Thiazoles such as diethylthiocarbamoylthio) benzothiazole; Nt-butyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl-2-
Sulfenamides such as benzothiazylsulfenamide, N, N'-diisopropyl-2-benzothiazylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide, tetraethylthiuram disulfide , Tetra-
Thiurams such as n-butylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide; zinc dimethylthiocarbamate, zinc diethylthiocarbamate, zinc di-n-butylthiocarbamate, zinc ethylphenyldithiocarbamate And carbamates such as sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate and iron dimethylthiocarbamate; and xanthates such as zinc butylthioxanthate. These vulcanization accelerators can be used alone or in combination of two or more. The amount of the vulcanization accelerator is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the ethylene copolymer rubber (A).

[0024] In addition to the above vulcanizing agents and vulcanization accelerators, vulcanization accelerating auxiliaries can be added as required. Examples of such vulcanization accelerating aids include metal oxides such as magnesium oxide, zinc white, litharge, leadtan, and lead white; organic acids (salts) such as stearic acid, oleic acid, and zinc stearate. And zinc white and stearic acid are particularly preferred. These vulcanization accelerators can be used alone or in combination of two or more. The amount of the vulcanization accelerating aid is usually 0.5 to 20 parts by weight based on 100 parts by weight of the ethylene copolymer rubber (A).

On the other hand, as the crosslinking agent constituting the component (B), for example, 1,1-di-tert-butylperoxy-3,
3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,3-bis (t Organic peroxides such as -butylperoxy-isopropyl) benzene. These crosslinking agents can be used alone or in combination of two or more. The amount of the crosslinking agent is usually 0.1 to 15 parts by weight, preferably 0.1 to 15 parts by weight, per 100 parts by weight of the ethylene copolymer rubber (A).
It is 5 to 10 parts by weight.

It should be noted that a crosslinking aid can be used in combination with the crosslinking agent. Examples of such a crosslinking assistant include sulfur and sulfur compounds such as sulfur and dipentamethylenethiuram tetrasulfide; ethylene di (meth)
Acrylate, polyethylene di (meth) acrylate,
Examples include polyfunctional monomers such as divinylbenzene, diallyl phthalate, triallyl cyanurate, metaphenylene bismaleimide, and toluylene bismaleimide; and oxime compounds such as p-quinone oxime and p, p'-benzoylquinone oxime. These crosslinking assistants can be used alone or in combination of two or more. The compounding amount of the crosslinking aid is usually 0.5 to 20 parts by weight based on 100 parts by weight of the ethylene copolymer rubber (A).

Next, as the foaming agent (C) used in the rubber composition of the present invention, for example, inorganic foaming agents such as ammonium carbonate, sodium bicarbonate and anhydrous sodium nitrate, dinitrosopentamethylenetetramine, N, N '-
Such as dimethyl-N, N'-dinitrosoterephthalamide, benzenesulfonyl hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide), 3,3'-disulfone hydrazide diphenyl sulfone, azobisisobutyronitrile, and azobisformamide; Organic foaming agents are included. In addition, along with these blowing agents, urea,
An organic acid-based or metal salt-based foaming aid may be used in combination.
These foaming agents and foaming assistants can be used alone or in combination of two or more. The compounding amount of the foaming agent is generally 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the ethylene copolymer rubber (A). If the amount is less than 0.5 part by weight, the foaming becomes insufficient, and so-called sponge rubber is not obtained. On the other hand, when the amount exceeds 30 parts by weight, it is difficult to obtain a uniform foam, which causes inconvenience such as poor appearance.

The rubber composition of the present invention may contain, if necessary, various other additives such as a filler, a softener, a plasticizer, a lubricant, a tackifier, an antioxidant, and an ultraviolet absorber. An agent can be compounded. As the filler, for example, SRF, GPF, FEF, HAF, ISAF, SA
Inorganic fillers such as carbon black such as F, FT, and MT, conductive carbon black, white carbon, fine particle magnesium silicate, heavy calcium carbonate, magnesium carbonate, clay, and talc; high styrene resin, cumarone indene resin, and phenol Organic fillers such as resin, lignin, modified melamine resin, petroleum resin and the like.
These fillers can be used alone or in combination of two or more.

Examples of the softener include process oils such as aromatic oils, naphthenic oils and paraffin oils, vegetable oils such as coconut oil, and the like, which are commonly used for rubber.
And synthetic oils such as alkylbenzene oils. Of these, process oils are preferred, and paraffin oil is particularly preferred. The softener may be used alone or
A mixture of more than one species can be used. The amount of the softening agent is usually 10 to 130 parts by weight, preferably 20 to 100 parts by weight based on 100 parts by weight of the ethylene copolymer rubber (A).
100 parts by weight.

In the rubber composition of the present invention, one or more kinds of other rubbers and / or resins can be mixed and used.

In preparing the rubber composition of the present invention, a conventionally known kneading machine, extruder, vulcanizing apparatus and the like can be used. (A) A vulcanizing agent and / or a cross-linking agent mixed with an ethylene copolymer rubber, (C) a compounding method of a foaming agent, a filler, a softening agent, and the like. (A)
After mixing an ethylene copolymer rubber, a filler, a softening agent, and the like, a method of adding (B) a vulcanizing agent and / or a crosslinking agent, and (C) a foaming agent using a roll or the like is used. However, the present invention is not limited to this.

Next, vulcanization and foaming may be carried out by, for example, placing the rubber composition of the present invention in a mold and raising the temperature, or vulcanizing or extruding the rubber composition by a method usually employed for the production of vulcanized rubber. After vulcanizing and foaming by heating in a vulcanizing tank after molding into an arbitrary shape using a molding machine, a vulcanized sponge rubber can be produced.

The rubber composition of the present invention is useful for sponge rubber applications such as weatherstrips around doors and trunk rooms of automobiles, gaskets for construction, hoses such as protector hoses and rolls.

[0034]

The present invention will now be described more specifically with reference to examples. However, the present invention is not limited to these embodiments. The percentages and parts in the examples are on a weight basis unless otherwise specified. The measurement and evaluation in Examples and Comparative Examples were performed by the following methods.

The α-olefin content (mol%) was measured by ¹³ C-NMR method. However, the content (mol%) of ethylene and α-olefin in each of Examples and Comparative Examples is a value when the total amount of these is 100 mol%. The iodine value was measured by an infrared absorption spectrum method. Mooney viscosity (ML _{1 + 4} , 100 ° C.) Measured under the conditions of measurement temperature of 100 ° C., preheating of 1 minute, and measurement of 4 minutes in accordance with JIS K6300. It was measured by GPC in Mw / Mn o-dichlorobenzene at 135 ° C. Glass transition temperature (Tg) Using a 910 type differential scanning calorimeter manufactured by DuPont Instruments (currently TIA Instruments), heat the sample to 180 ° C, then 10 ° C / min. The measurement was performed while cooling at a rate of -90 ° C and increasing the temperature at a rate of 20 ° C / min.

Tensile test According to JIS K6251, a No. 3 type test piece was used at a measuring temperature of 25 ° C. and a tensile speed of 500 mm / min., A tensile strength TB (kgf / cm ² ), and an elongation at break EB.
(%) Was measured. Low elongation stress (kgf / c) in accordance with JIS K6254
m ² ) was measured. The lower the value of the low elongation stress, the better the soft feeling. Compression set The tubular sponge rubber obtained as described above is
Cut into a length of 30 mm, put in a sponge rubber compression set measuring mold, compress 50% of the tube diameter, and then
After heat-treating the whole mold at 70 ° C. for 70 hours in a gear oven, it was measured in accordance with SRIS-0101.

Reference Example 1 (Production of Ethylene Copolymer Rubber) Into a stainless steel autoclave having a capacity of 3 liters and having been sufficiently purged with nitrogen, 1.3 liters of purified toluene and 1-liter
600 ml of octene, 7-methyl-1,6-
After 120 ml of octadiene was added and the temperature was raised to 30 ° C., the pressure inside the vessel was adjusted to 10 kg / cm ² while continuously supplying ethylene at a rate of 14 normal liters / minute. Separately, dimethylsilyl (t-butylamide) (2,3,4) dissolved in 3.0 ml of purified toluene was placed in a 50 ml-content glass flask containing a magnetic stirrer and sufficiently purged with nitrogen. 1.5 μmol of 5,5-tetramethyl-1-cyclopentadienyl) titanium dichloride and 0.75 mmol of triisobutylaluminum dissolved in 3.6 ml of purified toluene were added, and the mixture was stirred and reacted at room temperature for 30 minutes. Was. Next, 3.0 μmol of dimethylanilinium tetrakis (pentafluorophenyl) borate dissolved in 4.5 ml of purified toluene was added, and the mixture was stirred at room temperature for 20 minutes to react, thereby obtaining a polymerization catalyst.

The polymerization catalyst was added to the above autoclave to initiate polymerization. During the reaction, keep the temperature at 30 ° C and continuously supply ethylene,
g / cm ² and polymerization was carried out for 15 minutes. Next, after a small amount of methanol was added to stop the reaction, the mixture was dissolved by steam stripping and dried with a 6-inch roll to obtain 110 g of a polymer. This polymer has an ethylene content of 70 mol%, a 1-octene content of 30 mol%, an iodine value of 30, a Mooney viscosity of 90 and a Tg of -6.
8.7 ° C ethylene / 1-octene / 7-methyl-1,
It was a 6-octadiene copolymer.

Example 1 (Preparation and Evaluation of Rubber Composition) Using the copolymer rubber of Reference Example 1, the components shown in Table 1 except for the vulcanizing agent component and the foaming agent component were subjected to Banbury [contents] 1,700 ml, manufactured by Kobe Seiko Co., Ltd.], and kneaded at 60 rpm at 60 ° C. for 240 seconds to obtain Compound (i). Next, the vulcanizing agent component and the foaming agent component shown in Table 1 were added to Compound (i), and the mixture was kneaded with a 10-inch roll maintained at 60 ° C. for 5 minutes to obtain Compound (ii). Next, this compound (ii) was placed in a tube die (inner diameter: 14 mm, wall thickness: 1).
mm) using an extruder equipped with a head (die)
Extruded at a temperature of 70 ° C and a cylinder temperature of 60 ° C,
It was formed into a tube. This molded body was vulcanized at 220 ° C. for 5 minutes in a hot air vulcanizing tank to obtain a sponge rubber. Using this sponge rubber, low elongation stress is JIS K
6254, the tensile strength was measured in accordance with JIS K6251, and the compression set was measured in accordance with SRIS-0101. Table 2 shows the results.

Examples 2 to 3 In Example 1, 5-ethylidene-2-norbornene shown in Table 2 was used in place of 7-methyl-1,6-octadiene, and 5,7-dimethyl- Example 3 was performed in the same manner as in Example 1 except that 1,6-octadiene was used as Example 3. Table 2 shows the results. In Examples 1 to 3, the (A) ethylene copolymer rubber of the present invention is used, and a rubber composition for a sponge which is most suitable for producing a soft sponge without lowering compression set and tensile strength. It turns out that it is.

Comparative Examples 1-2 An ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber was produced using a Ziegler-Natta catalyst (a vanadium / aluminum catalyst). Comparative Example 1
In Example 2, a vulcanized rubber was obtained in Formulation A, and in Comparative Example 2, a vulcanized rubber was obtained in Formulation B. Comparative Example 2 is a soft sponge (low elongation stress is small) using the above copolymer rubber. Table 2 shows the results. Comparative Example 1 is a case in which a sponge was produced using the conventional ethylene / propylene / non-conjugated polyene copolymer rubber in the same formulation A as in the example, and had a low low elongation stress and lacked a soft feeling. Comparative Example 2 is a case where a sponge was produced with the blending recipe B such that the low elongation stress was small, and it is understood that the sponge is inferior in tensile strength and compression set.

[0042]

[Table 1]

* 1) Tokai Carbon Co., Ltd., Seast S * 2) Tokai Carbon Co., Ltd., Seast SO * 3) Idemitsu Kosan Co., Ltd., Diana Process Oil PW
-380 * 4) Maruo Calcium Co., Ltd., Super SS * 5) Sanyo Kasei Kogyo Co., Ltd., polyethylene glycol, molecular weight 4,000 * 6) Ouchi Shinko Kasei Kogyo Co., Ltd., NOCCELER
M * 7) NOCSELER, manufactured by Ouchi Shinko Kasei Kogyo Co., Ltd.
PZ * 8) Ouchi Shinko Kasei Kogyo Co., Ltd., NOCCELER
MDB * 9) Ouchi Shinko Kasei Kogyo Co., Ltd., NOCCELER
TRA * 10) Ouchi Shinko Kasei Kogyo Co., Ltd., VULNOC R * 11) Eiwa Kasei Kogyo Co., Ltd., OBSH (p, p'-)
Oxybisbenzenesulfonyl hydrazide)

[0044]

[Table 2]

[0045]

Industrial Applicability The rubber composition of the present invention has a good balance of flexibility, low compression set, and low-temperature properties, and is excellent in processing properties, and is used for weather strips such as around doors and trunk rooms of automobiles and for construction. Gaskets,
It is useful for hoses such as protector hoses and sponge rubber applications such as rolls.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Yasuda Inside JSR Co., Ltd. 2-11-24 Tsukiji, Chuo-ku, Tokyo

Claims (1)

[Claims] (A) ethylene, α- having 6 to 12 carbon atoms
Consisting of an olefin and a non-conjugated polyene,
A rubber composition for a sponge comprising an ethylene copolymer rubber satisfying the requirements of (1), (B) a vulcanizing agent and / or a crosslinking agent, and (C) a foaming agent as main components. The molar ratio of ethylene to an α-olefin having 6 to 12 carbon atoms (ethylene / α-olefin) is 40/60 to 80 /
20 Iodine value: 15 to 45 Mooney viscosity (ML _{1 + 4} , 100 ° C.): 40 to 150 Glass transition temperature (Tg) determined by a differential scanning calorimeter (DSC): −80 to −55 ° C.